This invention relates to disposable absorbent articles such as disposable diapers, and more particularly, disposable diapers for disposal of fecal matter, particularly of loose passage.
Infants excrete fecal matter often in the form of loose passages and there have already been proposed various disposable diapers and absorbent articles suitable for disposal of such loose passages. For example, Japanese Patent Application Disclosure No. 1987-125001 describes a disposable diaper including a topsheet formed with many apertures each having a diameter of 2xcx9c8 mm, an absorbent pad and a fibrous cushion layer made of synthetic fiber having a fineness of 6xcx9c12 d and disposed between the topsheet and the absorbent pad.
The fibrous cushion layer has a thickness of 4xcx9c100 mm and a density of 0.005xcx9c0.18 g/cm3. Loose passage moves through the apertures into the fibrous cushion layer and held therein without further moving in contact with a wearer""s skin. In this manner, one of causes for eruption and/or uncomfortableness due to wearing the diaper.
Japanese Patent Application Disclosure No. 1987-276002 describes a surface structure of a disposable diaper in which a topsheet is formed with many apertures each having an area of 7xcx9c50 mm2. The apertures are distributed at a pitch of 6xcx9c20 mm to have an open area ratio of 15xcx9c70% as a whole. A fibrous assembly layer underlying the topsheet is formed by component fibers heat-sealed together. This fibrous assembly layer has a thickness of 2xcx9c10 mm and a weight of 20xcx9c80 g/m2. In its wetted condition, the layer exhibits an elastic recovery from its compressed volume by 50% or more. This diaper of prior art is claimed to offer the same effect as that of the previously described diaper of prior art.
Japanese Patent Application Disclosure No. 1997-299402 describes an absorbent article including a liquid-pervious top layer, a liquid-impervious back layer, a liquid-absorbent core disposed between these two layer and a liquid-filtering layer disposed between the top layer and the core. The top layer is formed alternately with ridges and troughs, wherein each of the troughs is formed with a plurality of apertures and ribs projecting from peripheral edges of the respective apertures toward the back layer. The liquid-filtering layer presents a thickness of 1.0 mm or more under a pressure of 30 g/cm2 and has an average inter-fiber distance of 150 xcexcm or more. An effect offered by such absorbent article is similar to the effect of the previously described articles of prior art.
With the diaper and the absorbent article of prior art which have been described above, the fibrous cushion layer or the liquid-filtering layer underlies the top layer or the topsheet closely in contact with the lower surface thereof. Accordingly, the fibrous cushion layer or liquid-filtering layer likely chokes up the apertures of the top layer or topsheet. Loose passage can move into the fibrous cushion layer or liquid-filtering layer only in regions of such layer extending more or less into the respective apertures. While it will be possible for loose passage to move into the fibrous cushion layer or liquid-filtering layer even if each of the apertures has not adequately large open area, a rapid movement of loose passage can not be expected in this case. When it is tried to enlarge the open area of each aperture and thereby to accelerate the movement of loose passage, fibers of the fibrous cushion layer or the liquid-filtering layer extending into the respective apertures would discomfortably irritate a wearer""s skin. Since the fibrous cushion layer or liquid-filtering layer often comprises fibers of a relatively high fineness, such irritation is correspondingly intense and enlargement of the open area would be necessarily limited.
It is an object of this invention to provide a disposable absorbent article giving a wearer a good feeling to wear it and allowing fecal matter, particularly loose passage to rapidly move downward from a topsheet.
According to a first aspect of this invention, there is provided a disposable absorbent article having an inner surface intended to come in contact with a wearer""s skin and an outer surface opposed to the inner surface, the inner surface being provided with fecal matter retaining cavity or cavities adapted to receive fecal matter discharged on the inner surface so that the article is put on a wearer""s body with a region including the fecal matter retaining cavity or cavities placed against a predetermined region of a wearer""s hip extending around the anus, wherein: a fecal matter retaining layer having a thickness of 5xcx9c100 mm is formed with at least one said fecal matter retaining cavity comprising an opening having an area of 20xcx9c30000 mm2 and a depth of at least 2.5 mm and the retaining layer comprises a three dimensional network structure having air/water permeability in a thickness direction thereof defined between the inner and outer surfaces and in a planar direction thereof intersecting the thickness direction thereof at right angles and elastic compressivity in the thickness direction.
According to a second aspect of this invention, there is provided a disposable absorbent article comprising a hydrophobic topsheet having an opening through which fecal matter can pass, a fecal matter retaining layer, a moisture absorbent layer and a liquid-impervious backsheet successively laminated one with another in this order, wherein: the topsheet is formed with at least one the opening having an area of 20xcx9c30000 mm2; and the retaining layer is an elastic member having a thickness of 5xcx9c100 mm, air/water permeability in a thickness direction thereof and in a planar direction thereof intersecting the thickness direction at right angles, elastic recovery from a compressed state thereof of at least 50% in the thickness direction and a fecal matter retaining cavity formed immediately below the opening of the topsheet so as to have substantially the same open area as the area of the opening and a depth of at least 2.5 mm.